Powered wheelchairs are primary transportation tools for disabled persons. In order to conveniently control a powered wheelchair, a controller is mounted to an armrest of the powered wheelchair, and includes a standing operating lever for direction and speed control. In general, the controller is placed in front of the armrest such that a user can lay his/her arm on the armrest when controlling the standing operating lever. To prevent inadvertent operation of the controller from causing an accident when use of the controller is not needed, the controller is made to be rearward pivotable so as to be placed beside the armrest. However, the current controller is limited to horizontal rearward and forward shifting relative to the armrest. As such, the standing operating lever still protrudes from the armrest when the controller is pivotably disposed beside the armrest. As a result, inadvertent operation of the controller may still occur due to careless touch by the user's arm.